When you email a customer a document, they can also view it in document customer portal.

To do this, go to the "Marketing>Documents".

Find the Document you'd like to send and click the envelope button.

A pop-up will appear for you to choose the customer to send/assign it to.

Click the "Send Email" button.

The customer will receive this document or can view the document in the customer portal.

To view the document in the customer portal, they will log in to their portal and click "Finances>Documents".